1. Field of the Invention
The present invention relates to a camera, an accessory such as a photographic lens, and a camera system.
2. Description of the Related Art
A technique has been proposed in which a camera stores various types of information required for photographing in a read-only memory (ROM) (information fixed-storage circuit) included in an accessory, such as an interchangeable lens or a flash unit, mounted on the camera (camera body). Then, a microcomputer included in the camera body can designate an address of the ROM or a command via a microcomputer included in the accessory during photographing to allow the camera to obtain various information from the accessory.
Further, a technique has been proposed in which the name of a lens is transmitted via communication to enable identifying a type of the lens (Japanese Patent Application Laid-Open No. 2006-65068).
With the recent digitalization of cameras, information to be stored in a ROM of the accessory includes not only information required for photographing but also information appended to a photographed image and information used to make development, which converts photographed data into an image, high-quality. Attempts to acquire such information from the accessory as described above and to utilize the information on the camera side have been made.
Microcomputers for use in cameras and accessories have been made low in cost and large in capacity year after year to allow a huge amount of information to be stored on the accessory side. However, in order for a camera to acquire such a large amount of data from the accessory, an adequate length of communication time is required. Accordingly, if a photographer performs a photographing start operation during a period in which the camera is acquiring a large amount of data from the accessory, the photographer is required to wait until the camera reaches a photographing ready state since the camera is in the process of acquiring the data
Furthermore, for example, if a photographer performs a photographing start operation during a period in which a camera is acquiring data that does not have a fixed length, such as the name of an accessory or aberration of a lens, shutter release timing cannot be fixed since the photographer does not find when the camera reaches a photographing ready stat. Thus, the photographer cannot grasp photographing timing. Accordingly, the photographer cannot perform desirable photographing.